Polytetrafluoroethylene composite resin and preparation method thereof

Abstract

The invention discloses polytetrafluoroethylene composite resin and a preparation method thereof. The polytetrafluoroethylene composite resin comprises one or more modified fillers to enhance mechanical properties, increase dielectric constant and reduce dielectric loss. According to the preparation method of the polytetrafluoroethylene composite resin, the modified filler is added into the polytetrafluoroethylene which is uniformly mixed with the dispersion liquid, and the modified polytetrafluoroethylene composite resin is obtained through condensation treatment. The method is simple and easy to operate, and the influence of introduction of other solvents on the resin performance can be avoided while high-concentration dispersion can be realized.

Description

Technical Field

[0001] The present invention belongs to the field of chemical engineering, and particularly relates to a polytetrafluoroethylene composite resin containing a variety of fillers and a preparation method thereof. Background Art

[0002] Polytetrafluoroethylene (PTFE) is an excellent solid self-lubricating material, with excellent microwave electrical properties, extremely low friction coefficient, good chemical stability and thermal stability, and is widely used in the research and preparation of special materials in the fields of environmental protection, chemical engineering, machinery, electricity, construction, medical treatment, etc.

[0003] With the popularization of 5G communication, society has shown a high degree of informatization, and electronic communication has entered the high-frequency era. PTFE resins with excellent comprehensive performance are widely used in satellite communication, mobile communication receiving base stations, radar systems, automotive anti-collision systems, etc. However, unmodified PTFE has disadvantages such as poor wear resistance, low mechanical strength, and low dielectric constant. Therefore, it is necessary to use fillers to fill and compound-modify PTFE resins to enhance the mechanical properties of PTFE resins, increase the dielectric constant, and reduce the dielectric loss.

[0004] Adding TiO2 as a filler to PTFE polymers can significantly improve the dielectric and mechanical properties of the polymers, and it is an ideal material for high-dielectric fillers. It has a large specific surface area and strong surface polarity, and has a strong agglomeration tendency in the polymer matrix, so it must be modified to improve its compatibility and binding force with organic molecules. Summary of the Invention

[0005] The purpose of the present invention is to provide a PTFE composite resin and a preparation method thereof, and the PTFE composite resin has high mechanical strength, high dielectric constant, low dielectric loss, and excellent comprehensive performance.

[0006] In the first aspect of the present invention, a preparation method of a PTFE composite resin is provided, and the method includes: adding a coagulant to an emulsion containing PTFE, a first filler, and a second filler for coagulation treatment.

[0007] In some embodiments, the emulsion containing PTFE, a first filler, and a second filler is prepared by a method including the following steps: (a) adding a first filler to a PTFE emulsion, and obtaining a composite emulsion after mixing evenly; and (b) adding a second filler to the composite emulsion.

[0008] In some embodiments, the first filler is an organic filler, such as a heat-resistant aromatic resin, such as polyoxybenzoyl polyester, polyimide, tetrafluoroethylene-perfluoro(alkyl vinyl ether) copolymer (PFA), polyphenylene sulfide (PPS), polyether ether ketone (PEEK), etc.

[0009] In some embodiments, the first filler is an emulsion or a powder.

[0010] In some embodiments, the second filler is an inorganic filler, such as inorganic fibers or inorganic powders, such as glass fibers, graphite powder, glass beads, molybdenum disulfide powder, fluorinated mica powder, coke powder, carbon fiber, boron nitride powder, barium sulfate, carbon black including conductive carbon black, and minerals and ceramics such as TiO2, Al2O3, and SiO2.

[0011] In some embodiments, the first filler is a PFA emulsion, and the second filler is a mixture of TiO2 powder and SiO2 powder.

[0012] In some embodiments, the second filler is an inorganic filler modified with a modifier. Examples of the modifier include: silanes containing amino functional groups, phenyl-containing silanes, and / or soluble silicones; monocarboxylic acids of hydrocarbons having 12-20 carbon atoms; chromium complexes of aliphatic carboxylic acids, etc.

[0013] In some embodiments, the silane containing an amino functional group is selected from γ-aminopropyltriethoxysilane (H2N(CH2)3Si(OC2H5)3) (KH550), meta- or para-aminophenyltriethoxysilane (H2N-C6H4-Si(OC2H5)3), γ-ureidopropyltriethoxysilane (H2NCONH(CH2)3Si(OC2H5)3), N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane (H2N(CH2)2NH(CH2)3SiCH3(OCH3)2), and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane (H2N(CH2)2NH(CH2)3Si(OCH3)3).

[0014] In some embodiments, the phenyl-containing silane is selected from phenyltrimethoxysilane, phenyltriethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, p-chlorophenyltrimethoxysilane, p-bromomethylphenyltrimethoxysilane, and diphenylsilanediol.

[0015] In some embodiments, the modifier is selected from γ-aminopropyltriethoxysilane (KH550).

[0016] In some embodiments, modifying with a modifier includes adding an inorganic filler to a modifier solution for modification treatment and optionally drying. In some embodiments, the modifier solution is a solution of the modifier in an organic solvent, examples of which include but are not limited to anhydrous methanol, anhydrous ethanol, anhydrous isopropanol, etc. In some specific embodiments, the modifier solution contains about 10 wt% to 30 wt% of the modifier, such as about 15 wt% to 25 wt% of the modifier. In some embodiments, the modifier solution contains about 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15 wt%, 16 wt%, 17 wt%, 18 wt%, 19 wt%, 20 wt%, 21 wt%, 22 wt%, 23 wt%, 24 wt%, 25 wt%, 26 wt%, 27 wt%, 28 wt%, 29 wt%, 30 wt% or any value therebetween of the modifier.

[0017] In some embodiments, the time of the modification treatment is selected from 30 - 50 min, such as 35 - 45 min, such as 30, 35, 40, 45 or 50 min, preferably 40 min.

[0018] In some embodiments, the weight ratio of TiO2 powder to SiO2 powder in the second filler is selected from about 10 - 60, such as about 15 - 50, such as about 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60 or any value therebetween.

[0019] In some embodiments, the weight ratio of the modifier contained in the second filler to the total weight of TiO2 and SiO2 powders is selected from about 1 - 5, such as about 1, 2, 3, 4, 5 or any value therebetween.

[0020] In some embodiments, the TiO2 powder is rutile-type nano-TiO2 powder and the SiO2 powder is nano-SiO2 powder. The rutile-type nano-TiO2 has a dense structure and higher refractive index, specific gravity and chemical stability than other crystal forms.

[0021] In some embodiments, the particle size of TiO2 is 10 - 50 nm, such as 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50 nm or any value therebetween.

[0022] In some embodiments, the particle size of SiO2 is 10 - 50 nm, such as 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50 nm or any value therebetween.

[0023] In some embodiments, the addition amount of the second filler, especially the filler modified with a modifier, is 0.5 - 5.5 wt% of the composite emulsion, such as 1.0 - 4.0 wt%, such as 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5 wt% or any value therebetween.

[0024] In some embodiments, the solid content of the composite emulsion is 5 - 10%, such as 5%, 6%, 7%, 8%, 9%, 10% or any value therebetween.

[0025] In some embodiments, the first filler is a PFA emulsion, and the mass ratio of the PTFE emulsion to the PFA emulsion is selected from about 5 - 15, such as about 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 or any value therebetween.

[0026] In some embodiments, the solid content of the PTFE emulsion is about 25 - 35%, such as about 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35% or any value therebetween.

[0027] In some embodiments, the first filler is a PFA emulsion, and the solid content of the PFA emulsion is about 20 - 30%, such as about 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30% or any value therebetween.

[0028] In some embodiments, the coagulation includes stirring at a coagulation temperature of 25 to 75 °C, preferably 35 to 55 °C, at a stirring rate of 100 to 800 rpm, preferably 200 to 400 rpm. Specifically, the coagulation temperature can be 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75 °C or any value therebetween. The stirring rate for the coagulation can be 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800 rpm or any value therebetween. The coagulation time is related to the coagulant used and its amount, and those skilled in the art can select according to needs. In some embodiments, the coagulation time can be 10 to 60 min, such as 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60 min or any value therebetween.

[0029] In some embodiments, the coagulant is ammonium carbonate, ammonium bicarbonate, ammonium carbamate or any combination thereof.

[0030] In some embodiments, the method further includes a step of drying after the coagulation treatment, such as hot air drying at 120 °C.

[0031] In some embodiments, the method further includes a step of adding deionized water to the composite emulsion for dilution.

[0032] In a specific embodiment, the method includes: adding a PTFE dispersion emulsion and a tetrafluoroethylene-perfluoro(alkyl vinyl ether) copolymer (PFA) emulsion into a coagulation treatment container, mixing them evenly, diluting with deionized water while adjusting the temperature of the coagulation treatment to obtain a composite emulsion, adding a modified second filler to the composite emulsion, mixing evenly, and then adding a coagulant for coagulation treatment, wherein the modified second filler is obtained by modifying TiO2 and SiO2 powders with a modifier solution.

[0033] In a second aspect of the present invention, there is provided a PTFE composite resin prepared by using the method according to the first aspect of the present invention.

[0034] The PTFE composite resin prepared by the method of the present invention has excellent mechanical strength and dielectric loss, and is particularly suitable for the chemical industry, machinery industry, electronics and electrical, coating consumer goods, as well as the construction industry, medical industry and aviation field, etc. Detailed Embodiments

[0035] To make the objectives, technical solutions and advantages of the present invention more clearly understood, the following further details the present invention in conjunction with embodiments. The specific embodiments described herein are only used to explain the present invention and are not used to constitute any limitation to the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessarily confusing the concepts of the present disclosure. Such structures and technologies have also been described in many publications.

[0036] Definition

[0037] Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as commonly used in the field to which the present invention belongs. For the purpose of explaining this specification, the following definitions will be applied, and when appropriate, terms used in the singular form will also include the plural form, and vice versa.

[0038] Unless the context clearly indicates otherwise, the expressions "a" and "an" used herein include plural referents.

[0039] In the present disclosure, the expression "about" is as understood by those of ordinary skill in the art and varies within a certain range according to the context in which it is used. If those of ordinary skill in the art do not understand the use of this term according to the context in which it is used, "about" will mean up to plus or minus 10% of a specific value.

[0040] In the present disclosure, the terms "PTFE" and "polytetrafluoroethylene" are used interchangeably herein and refer to a polymer containing tetrafluoroethylene monomer units, which is formed by the polymerization reaction of tetrafluoroethylene monomers.

[0041] In the present disclosure, the term "PFA" refers to a copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether, also known as perfluoroalkylated compound or soluble polytetrafluoroethylene.

[0042] In the present disclosure, the term "emulsion" refers to an oil-in-water type emulsified composition. In the present disclosure, the PTFE emulsion is preferably a PTFE polymerization stock solution formed by the emulsion polymerization method of tetrafluoroethylene (TFE). For example, it can be a homopolymer of TFE. The weight average molecular weight of PTFE in the PTFE emulsion can be 1×10 5 ~1×10 8 ,especially 1×10 6 ~1×10 7。The average particle size of the PTFE emulsion can be 0.01 to 5.0 μm, particularly 0.1 - 0.5 μm. Similarly, the PFA emulsion is preferably a PFA polymerization stock solution produced by emulsion polymerization, for example, a polymerization stock solution obtained by copolymerizing TFE and perfluoropropyl vinyl ether (PAVE) in a conventional aqueous medium by emulsion polymerization. The average particle size of the PFA particles in the PFA emulsion can be 0.01 to 5.0 μm, particularly 0.1 - 0.5 μm.

[0043] The term "modifier" refers to a class of additives added to the filler to help achieve the desired surface properties of the filler, so as to facilitate the uniform mixing of the filler with PTFE. In addition to obtaining the desired surface properties, these additives also help to control application properties such as the stability and ease of application of the filler.

[0044] In the present disclosure, the term "coagulant" refers to electrolytes such as salts that are mixed into a turbid emulsion to rapidly coagulate an emulsion complex containing a PTFE emulsion, a soluble polytetrafluoroethylene (PFA) emulsion, and deionized water. For example, ammonium carbonate, ammonium bicarbonate, ammonium carbamate, aluminum trichloride, aluminum sulfate, ferrous sulfate, ferric trichloride, ferric sulfate, calcium oxide, calcium hydroxide, sodium hydroxide, sodium carbonate, and the like.

[0045] In the present disclosure, unless otherwise specified, the materials used are all products that can be obtained through regular commercial purchases.

[0046] Examples are provided below to help understand the present invention. However, it should be understood that these examples are only used to illustrate the present invention and do not constitute any limitation. The actual protection scope of the present invention is set forth in the claims. It should be understood that any modifications and changes can be made without departing from the spirit of the present invention.

[0047] Examples

[0048] Example 1:

[0049] Formulation of modified filler:

[0050]

[0051] 1) Add TiO2 and SiO2 powders to the KH550 / absolute ethanol mixture. Stir at low speed at room temperature for 40 min, then filter to remove the filtrate, and dry at 140 °C with hot air for 4 h to obtain the modified filler.

[0052] 2) In a 5L coagulation barrel with a heating system and mechanical stirring, 1100g of PTFE emulsion with a solids content of 28% and 90g of PFA emulsion with a solids content of 28% are added in sequence. 2810g of deionized water is added, and the temperature is raised to 45°C. After stirring at a low speed for 2 minutes, the stirring is stopped. The purpose is to mix the PTFE and PFA emulsions evenly to obtain a composite emulsion with a solids content of 8%.

[0053] 3) The modified filler is added to the composite emulsion and stirred at a low speed for 2 minutes. 100g of coagulant ammonium carbonate is added, and the stirring speed is adjusted to 300rpm. After coagulation for 20 minutes, the resin is completely dehydrated, filtered, and dried at 120°C with hot air for 8 hours to obtain the composite resin. Tests such as tensile strength, elongation at break, relative density, dielectric constant, and dielectric loss are carried out.

[0054] Example 2:

[0055] Formulation of the modified filler:

[0056]

[0057] 1) The TiO2 and SiO2 powders are added to the KH550 / absolute ethanol mixture. At room temperature, after stirring at a low speed for 40 minutes, the filtrate is removed by filtration, and dried at 140°C with hot air for 4 hours to obtain the modified filler.

[0058] 2) In a 5L coagulation barrel with a heating system and mechanical stirring, 1300g of PTFE emulsion with a solids content of 28% and 144g of PFA emulsion with a solids content of 28% are added in sequence. 2556g of deionized water is added, and the temperature is raised to 45°C. After stirring at a low speed for 2 minutes, the stirring is stopped. The purpose is to mix the PTFE and PFA emulsions evenly to obtain a composite emulsion with a solids content of 10%.

[0059] 3) The modified filler is added to the composite emulsion and stirred at a low speed for 2 minutes. 100g of coagulant ammonium carbonate is added, and the stirring speed is adjusted to 300rpm. After coagulation for 20 minutes, the resin is completely dehydrated, filtered, and dried at 120°C with hot air for 8 hours to obtain the composite resin. Tests such as tensile strength, elongation at break, relative density, dielectric constant, and dielectric loss are carried out.

[0060] Example 3:

[0061] Formulation of the modified filler:

[0062]

[0063] 1) The TiO2 and SiO2 powders are added to the KH550 / absolute ethanol mixture. At room temperature, after stirring at a low speed for 40 minutes, the filtrate is removed by filtration, and dried at 140°C with hot air for 4 hours to obtain the modified filler.

[0064] 2) In a 5L coagulation barrel with a heating system and mechanical stirring, 685g of PTFE emulsion with a solids content of 28% and 57g of PFA emulsion with a solids content of 28% are added in sequence. 3258g of deionized water is added, and the temperature is raised to 45°C. After stirring at a low speed for 2 minutes, the stirring is stopped. The purpose is to mix the PTFE and PFA emulsions evenly to obtain a composite emulsion with a solids content of 5.2%.

[0065] 3) The modified filler is added to the composite emulsion and stirred at a low speed for 2 minutes. 100g of coagulant ammonium carbonate is added, and the stirring speed is adjusted to 300rpm. After coagulation for 20 minutes, the resin is completely dehydrated, filtered, and dried at 120°C with hot air for 8 hours to obtain the composite resin. Tests such as tensile strength, elongation at break, relative density, dielectric constant, and dielectric loss are carried out.

[0066] Example 4:

[0067] The difference from Example 1 lies in the formula of the modified filler:

[0068]

[0069] Example 5:

[0070] The difference from Example 1 lies in the formula of the modified filler:

[0071]

[0072] Example 6:

[0073] The difference from Example 1 is that the coagulation temperature of the composite emulsion is 60°C and the stirring speed is 600rmp.

[0074] Example 7:

[0075] The difference from Example 1 is that the coagulation temperature of the composite emulsion is 25°C and the stirring speed is 100rmp.

[0076] Comparative Example 1:

[0077] 1) In a 5L coagulation barrel with a heating system and mechanical stirring, 1300g of PTFE emulsion with a solids content of 28% and 144g of PFA emulsion with a solids content of 28% are added in sequence. 2556g of deionized water is added, and the temperature is raised to 45°C. After stirring at a low speed for 2 minutes, the stirring is stopped. The purpose is to mix the PTFE and PFA emulsions evenly to obtain a composite emulsion with a solids content of 10%.

[0078] 2) 100g of coagulant ammonium carbonate is added to the composite emulsion, and the stirring speed is adjusted to 300rpm. After coagulation for 20 minutes, the resin is completely dehydrated, filtered, and dried at 120°C with hot air for 8 hours to obtain the composite resin. Tests such as tensile strength, elongation at break, relative density, dielectric constant, and dielectric loss are carried out.

[0079] Comparative Example 2:

[0080] Formulation of modified filler:

[0081]

[0082] 1) Add TiO2 and SiO2 powders to the KH550 / absolute ethanol mixture. At room temperature, stir slowly for 40 min, then filter to remove the filtrate, and dry in hot air at 140 °C for 4 h to obtain the modified filler.

[0083] 2) Add 742 g of PTFE emulsion with a solid content of 28% to a 5 L coagulation barrel equipped with a heating system and mechanical stirring. Add 3258 g of deionized water and heat up to 45 °C to obtain a composite emulsion with a solid content of 5.2%.

[0084] 3) Add the modified filler to the composite emulsion, stir slowly for 2 min, add 100 g of coagulant ammonium carbonate, adjust the stirring speed to 300 rpm, coagulate for 20 min, then filter and dry in hot air at 120 °C for 8 h to obtain the composite resin. Perform tests on tensile strength, elongation at break, relative density, dielectric constant, dielectric loss, etc.

[0085] Test the tensile strength, elongation at break, relative density, dielectric constant, dielectric loss, etc. of the PTFE composite resins prepared in Examples 1-7 and Comparative Examples 1-2. The test results are shown in Table 1:

[0086] Table 1 Test data table of examples and comparative examples

[0087]

[0088]

[0089] The technical solution of the present invention is not limited to the limitations of the above specific embodiments. Any technical deformation made according to the technical solution of the present invention falls within the protection scope of the present invention.

Claims

1. A preparation method of PTFE composite resin, characterized in that, The method includes: adding a coagulant to an emulsion containing PTFE, a first filler, and a second filler for coagulation treatment. Preferably, the preparation method includes the following steps: (a) adding a first filler to an emulsion of PTFE, and obtaining a composite emulsion after mixing evenly; and (b) adding a second filler to the composite emulsion.

2. The preparation method according to claim 1, characterized in that, The first filler is an organic filler, such as a heat-resistant aromatic resin, such as polyoxybenzoyl polyester, polyimide, tetrafluoroethylene-perfluoro(alkyl vinyl ether) copolymer (PFA), polyphenylene sulfide (PPS), polyether ether ketone (PEEK), and the like.

3. The preparation method according to claim 1, characterized in that, The first filler is in the form of an emulsion or powder.

4. The preparation method according to claim 1, characterized in that, The second filler is an inorganic filler. Preferably, the second filler is a mixture of one or more selected from the following: inorganic fibers or inorganic powders, such as glass fibers, graphite powder, glass beads, molybdenum disulfide powder, fluorinated mica powder, coke powder, carbon fibers, boron nitride powder, barium sulfate, carbon black including conductive carbon black, and minerals and ceramics, such as TiO2, Al2O3, and SiO2, and the like.

5. The preparation method according to claim 4, characterized in that, The second filler is a modified inorganic filler. Preferably, the modification treatment is carried out using a modifier, and the modifier includes: silanes containing amino functional groups, phenyl-containing silanes, and / or soluble silicone; monocarboxylic acids of hydrocarbons having 12-20 carbon atoms; chromium complexes of aliphatic carboxylic acids, and the like.

6. The preparation method according to claim 5, characterized in that, The silanes containing amino functional groups are selected from γ-aminopropyltriethoxysilane (H2N(CH2)3Si(OC2H5)3), meta- or para-aminophenyltriethoxysilane (H2N-C6H4-Si(OC2H5)3), γ-ureidopropyltriethoxysilane (H2NCONH(CH2)3Si(OC2H5)3), N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane (H2N(CH2)2NH(CH2)3SiCH3(OCH3)2), and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane (H2N(CH2)2NH(CH2)3Si(OCH3)3), and / or The phenyl-containing silanes are selected from phenyltrimethoxysilane, phenyltriethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, p-chlorophenyltrimethoxysilane, p-bromomethylphenyltrimethoxysilane, and diphenylsilanediol.

7. The preparation method according to claim 5, characterized in that, The modification treatment includes the step of adding the inorganic filler to the modifier solution for modification, and optionally the step of drying. Preferably, the modifier solution is a solution of the modifier in an organic solvent, and the organic solvent is selected from anhydrous methanol, anhydrous ethanol, anhydrous isopropanol, and the like. Preferably, the modifier solution contains about 10 wt% to 30 wt% of the modifier, preferably about 15 wt% to 25 wt% of the modifier.

8. The preparation method according to claim 5, characterized in that, The time of the modification treatment is selected from 30 - 50 min. Preferably, the time of the modification treatment is 35 - 45 min. Preferably, the time of the modification treatment is 30, 35, 40, 45 or 50 min. Preferably, the time of the modification treatment is 40 min.

9. The preparation method according to claim 1, characterized in that, The second filler comprises TiO2 and SiO2 powders, and the weight ratio of TiO2 powder to SiO2 powder is selected from about 10 - 60, preferably from about 15 - 50.

10. The preparation method according to claim 9, characterized in that, The weight ratio of the modifier to the total weight of TiO2 and SiO2 powders is selected from about 1 - 5, such as about 1, 2, 3, 4, 5 or any value therebetween.

11. The preparation method according to claim 9, characterized in that, Wherein the TiO2 has a particle size of 10 - 50 nm, and / or the SiO2 has a particle size of 10 - 50 nm.

12. The preparation method according to claim 1, characterized in that, The addition amount of the second filler is 0.5 - 5.5 wt% of the composite emulsion, and the solid content of the composite emulsion is about 5 - 10%; and / or The first filler is a PFA emulsion, and the mass ratio of the PTFE emulsion to the PFA emulsion is about 5 - 15; and / or The solid content of the PTFE emulsion is about 25 - 35%, such as about 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35% or any value therebetween; and / or The first filler is a PFA emulsion, and the solid content of the PFA emulsion is about 20 - 30%; and / or The coagulation treatment includes stirring at a coagulation temperature of 25 - 75 °C, preferably 35 - 55 °C, at a stirring rate of 100 - 800 rpm, preferably 200 - 400 rpm; and / or The coagulant is ammonium carbonate, ammonium bicarbonate, ammonium carbamate or any combination thereof; and / or The method further includes a step of drying after the coagulation treatment; and / or The method further includes a step of adding deionized water to the composite emulsion for dilution.

13. A PTFE composite resin, characterized in that, The PTFE composite resin is prepared by the method according to any one of claims 1 - 12.

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